Spongy bones protect woodpeckers' brains

Woodpeckers, as we all know, slam their little beaks into trees hard enough to make a loud knocking sound. So why aren't their brains turned to jelly?

This is pretty interesting, so pay attention. It could be on the test.

In the late 1970s, a trio of researchers used cameras capable of shooting 2,000 frames a second to film a tame acorn woodpecker pecking away at some sort of hard surface.

What they found was that the bird's beak was smacking into the surface at an impact deceleration, whatever that is, of more than 1,000 times the force of gravity.

So why aren't woodpeckers knocking themselves silly?

For one thing, the bones of our skulls are sort of spongy, but the bones of a woodpecker's skull are really, really spongy.

Those spongy bones act as sort of a shock absorber.

Next, woodpeckers have fairly small brains that fit very tightly in the skull.

So the brain doesn't move around much in the skull, something that prevents what are known as "contrecoup" injuries - brain bruising.

And since the brain is small it has a high ratio of surface area to weight. That means the force of the impact from all their drilling is spread out over a relatively wide area.

One more thing: If you were in a serious car accident, you might suffer what is called a diffuse axonal injury. What happens is, the sudden deceleration and rotational stress twists parts of your brain off each other.

That sounds gross, doesn't it?

However, when a woodpecker pecks, it hits its target in an exact straight line so there is no rotational stress on the brain.